1. Field of the Invention
This invention relates to a power semiconductor structure and a fabrication method thereof, and more particularly relates to a power semiconductor with a field effect rectifier and a fabrication method thereof.
2. Description of Related Art
Switching speed is an important issue for trenched power semiconductor applications. For high frequency operations of power semiconductors, the increasing of switching speed is helpful for reducing switching loss. However, the power transistor has its structural limitation that the switching speed thereof is restricted by the reverse recovery time of body diode located between source and drain electrodes.
In order to resolve this problem, as shown in FIG. 1, a typical method is to connect a schottky diode SD1 between the source electrode and the drain electrode of the transistor T1 as a current path to replace the body diode D1. Since the turn-on voltage of the schottky diode SD1 is significantly lower than that of the body diode D1, current flow from the source electrode would be directed to the current path including the schottky diode SD1 and the body diode D1 would not be turned on.
Although it is an effective method to integrate a schottky diode SD1 to the transistor for solving the problem of long reverse recovery time due to body diode D1, typical transistor fabrication process does not suitable for the formation of the additional schottky diode. The fabrication process must be changed and some additional fabrication steps are usually unpreventable. As a result, the fabrication process becomes quite complicated and the cost is enhanced.